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The Qiongdongnan and Yinggehai Basins are important petroliferous basins. To study the Cenozoic subsidence characteristics of these two basins, their controlling factors, and their implications, we studied the basins’ subsidence characteristics via one-dimensional, two-dimensional, and holistic subsidence. Then, we compared the basins’ subsidence characteristics based on the evolution of several particular geological processes that occurred in the South China Sea (SCS) and adjacent areas. The results indicated that the change in the holistic subsidence of both basins occurred episodically. In addition, the subsidence in these two basins differed, including their subsidence rates, the migration of the depocenters, and the changes in the holistic subsidence. The dynamic differences between the two basins were the main factors controlling the differences in the subsidence in the two basins. In the Qiongdongnan Basin, the subsidence characteristics were primarily controlled by the mantle material flowing under the South China Block in the Eocene and the spreading of the SCS from the Oligocene to the Miocene. In the Yinggehai Basin, the subsidence characteristics were primarily controlled by the coupling between the uplift of the Tibetan Plateau and the strike-slip motion of the Red River Fault before the Early Miocene and by only the effect of the strike-slip motion of the Red River Fault from the Middle Miocene to the Late Miocene. Since the Pliocene, the subsidence characteristics of both basins have been principally controlled by the dextral strike-slip motion of the Red River Fault. The major faults contributed to the spaciotemporal variations in the subsidence within each basin.

The topological pseudospin-dependent edge states for sound and light are achieved simultaneously in phoxonic crystals (PxCs). By studying the topological phase transition mechanisms, we find that photonic bands can be inverted by changing the distance from the center of rods to the center of the unit cell, and phononic bands can be inverted by modifying the rotation angle of rods. Based on different adjustment schemes for light and sound, band inversions of both photonic and phononic modes are realized by simultaneously deforming the lattice and rotating the rods. Dual topological pseudospin-dependent edge states thus can be observed at the domain wall interfaces between two PxCs with distinct topological phases. The pseudospin-dependent one-way propagations and the topologically robust propagations against three types of defects for both light and sound are further numerically demonstrated. The proposed PxCs provide a platform for designing topologically integrated management of photons and phonons.

Degradation of dysfunctional, damaged, or misfolded proteins is a crucial component of the protein quality control network to maintain cellular proteostasis. Dysfunction in proteostasis regulation due to imbalances in protein synthesis, folding, and degradation challenges the integrity of the cellular proteome and favors the accumulation of aggregated proteins that can damage cells by a loss of their functions and/or a gain of adverse functions. Ubiquitination is an essential player in proteostasis regulation but also in orchestrating signaling pathways in response to various stress conditions. Both cellular degradation systems, the proteasome and autophagy, employ ubiquitin for selection and targeting of substrates to the degradative machineries. Here we summarize the manifold functions of ubiquitin in protein degradation and discuss its emerging role in the formation of biomolecular condensates through liquid-liquid phase separation, which allows spatiotemporal regulation of protein quality control.

In this paper, simultaneous zero refractive indices (ZRIs) for both sound and light are realized on the basis of a 2D triangular lattice phoxonic crystal (PxC) with C6v symmetry. For the phononic mode, accidental phononic Dirac degeneracy at the center of Brillouin zone (BZ) occurs at a relatively high frequency which leads to the failure of the efficient medium theory; hence, it is no longer applicable to the realization of acoustic ZRI. We thus turn to a low-frequency phononic Dirac cone located at K point, the corner of the BZ, which shows in-phase pressure field oscillations in expanded unit cells. Using zone folding, we further reveal the cause for the characteristic of acoustic ZRI. For the photonic mode, a low-frequency photonic Dirac-like cone can be achieved by adjusting the geometric parameter due to the high contrast permittivity between scatterers and the matrix. When the phononic and photonic low-frequency Dirac dispersions coexist, the PxC can be mapped into a zero-index material for both sound and light at the same time. The new mechanism for simultaneously controlling sound and light helps to achieve acousto-optic synchronous cloaking and unidirectional transmission, which are numerically demonstrated.

Reverse-time migration (RTM) has been widely used for imaging subsurface structure in seismic surveys for hydrocarbon resource explorations. It has been adopted for migrating ground penetrating radar (GPR) data due to the kinematics and dynamics similarity between electromagnetic and seismic waves. Low-frequency migration artifacts happen when the conventional image condition is used, especially when the migration model is not smooth. In this abstract, we decompose the wavefield into left-and right-going wavefield based on the Hilbert transform, and then apply the image condition to generate migration image in which the low-frequency noise are largely eliminated. Synthetic results suggest more clear image can be obtained using the isolated wavefiled to construct RTM image.

Migration of ground penetrating radar (GPR) data transforms the event occurred in the subsurface to the real location in either space or time domain, it provides more accurate image of subsurface. In order to improve the migration image quality, a deblurring filter is designed to deblur the reverse time migration (RTM) image. Numerical example demonstrates the deblurred RTM image is much improved, compared with the raw RTM image.

Reverse-time migration (RTM) is used for subsurface imaging to handle complex velocity models including steeply dipping interfaces and dramatic lateral variations and promises better imaging results compared to traditional migration method such as Kirchhoff migration algorithm. RTM has been increasingly used in seismic surveys for hydrocarbon resource explorations. Based on the similarity of kinematics and dynamics between electromagnetic wave and elastic wave, we develop pre-stack RTM method and apply it to process ground penetrating radar (GPR) data. Finite-difference time domain (FDTD) numerical method is used to simulate the electromagnetic wave propagation including forward and backward extrapolations, the cross-correlation imaging condition is used to obtain the final image. In order to provide a velocity model with relatively higher accuracy as the initial velocity model for RTM, we apply a full waveform inversion (FWI) in time domain to estimate the subsurface velocity structure based on reflection radar data. For testing the effectiveness of the algorithm, we have constructed a complex geological model, common-offset radar data and common-shot profile (CSP) radar reflection data are synthesized. All data are migrated with traditional Kirchhoff migration method and pre-stack RTM method separately, the migration results from pre-stack RTM show better coincidence with the true model. Furthermore, we have performed a physical experiment in a sandbox where a polyvinyl chloride (PVC) box is buried in the sand, the obtained common-offset radar data and common-shot radar data are migrated by using Kirchhoff migration method and pre-stack RTM algorithm separately, the pre-stack RTM result shows that RTM algorithm could get better imaging results.

A stepped-frequency continuous wave (SFCW) airborne ground penetrating radar (GPR) system was built using a vector network analyzer (VNA), an optical-to-electric ( \mmb O/\mmb E) converter, an electric-to-optical ( \mmb E/\mmb O) converter, and the resistively loaded planer dipole antennas. The resistively loaded antennas are based on the Altshuler discrete resistive loading approach. The distance from the loading point to the feeding point and the resistance has been optimized; in addition, a balun at the feeding point was introduced to convert the unbalanced signal from the coax to balanced signal. Test results show that the manufactured antennas have a wide bandwidth frequency range from 55 to 275 MHz. A laboratory experiment using the developed system was conducted in a building with high ceilings. The results registered all basic features including the ground, sub-ground surface, and the lamp hanging from the ceiling. Numerical modeling by finite-difference time-domain (FDTD) method using two-dimensional (2-D) transverse electric (TE) verifies the presence of these registered features in the measured airborne data. A bedrock outcrop in ice sheet model is reconstructed based on a piece of real airborne GPR data, the modeling profile results show excellent consistent with the observed data. The capability of airborne GPR detection of subsurface features is clearly validated.

With the increasing development of information technology, engineering training system of the traditional colleges and universities has not completely satisfied the current practical tasks, for purpose of upgrading and innovation of teaching system in engineering training. An engineering training mobile service system based on the mobile internet of things is proposed in this paper. The system is developed based on the Android platform. Through the Android intelligent terminal and workshop wireless network system, it realizes mobile monitoring and management of the workshop production by the combination of pushing information. The implementation and operation of the system completely changed the traditional way of practice operation, greatly enhancing the real-time, timeliness and agility of information interaction between teacher and student in the practical operating process. It makes training more convenient, efficient and flexible.

Summary Traditional finite difference time domain (FDTD) is classic numerical method for solving wave propagation problems such as electromagnetic wave, seismic wave and acoustic wave. As for airborne GPR simulation, modeling space is so large that memory consuming is pretty huge; on the other hand, the area between source antenna and ground surface is homogenous medium – air, where analytic solution could be adopted. We use analytic solution in free space and take use of numerical solution – FDTD in the underground. Different solutions are adopted in different region, and both of them are combined together, that is known as the multi-region FDTD (MR/FDTD) method. The MR/FDTD we discussed here is not the same as before. As we select one face instead of a closed surface as integration surface. The validity of the MR/FDTD method for airborne GPR simulation is investigated by numerical experiments in the work.

Crosshole ground penetrating radar (GPR) tomography play an important role in geoscientific and engineering investigations recent years. Traditional tomography based on ray theory can't provided high resolution images. Here, we realized a full-waveform inversion which can exploit all information present in the observed data. The inversion use the steepest descent method based on a finite-difference time-domain inversion of Maxwell's equations. We build a complex model which have three layers and two subwavelength pipes. Synthetic data of this model was applied by using the full-waveform inversion. Three results of different setting of FWI are given and compared. In the last experimentation the source wavelet is estimated and this procedure is very necessary. This work shows FWI can provide high solution images of sufwavelength but the results of simultaneous inversion based on the estimated wavelet are not good enough. We will continue to improve the method in the future.

The accurate inspection of the duct condition in post-tensioned prestressed concrete (PPC) is an essential part of GPR concrete inspection. The purpose is to inspect the grouting condition of the ducts where the strands are located, to find out if there is a void in the ducts, and if any water exists. In order to investigate the radar image characteristics of different PPC duct defects, a number of model girders were manufactured. Three major ducts are included in our study: (1) well grouted and no void (normal condition); (2) the duct is half filled, and the void is filled by water or air; and (3) the duct is not filled at all, and the duct is water or air filled. The data corresponding to seven different situations are acquired and processed. It is found that the radar can detect the first interface in the duct, and the detailed structure inside the duct cannot be ?seen? from the images directly. Characteristic curves greatly help the interpretation. A completely void duct is the easiest to differentiate from the others. The signature for this situation is characterized by a strong and clear reflection interface which becomes weaker as the void is water filled. The normal condition shows the weakest reflection interface. As for the half void situation, the front scan shows a similar result to the normal condition whether it is water or air filled, and the back scan shows similar features to the completely void situation. The experiment and analysis is helpful and instructive for practical engineering inspection.